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No official flood warning is active nearby and the closest river stations are within normal ranges.
Updated 2026-10-10 12:34:30 UTC · Official GOV.UK warnings · Flood preparation & help guide
Grendon Underwood is a village and civil parish in west Buckinghamshire, England, near the border with Oxfordshire. The village sits between Woodham and Edgcott, near the Roman road Akeman Street, and around 10 miles (16 km) north-west of Aylesbury. At the 2011 Census, the population of the civil parish was 1,625.
Towns and villages near Grendon Underwood with a page of their own: the homes in a flood risk area there, the nearest river gauges, and recorded floods.
Place names: Contains OS data © Crown copyright and database rights 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Contains National Statistics data © Crown copyright and database right 2026. Licensed under the Open Government Licence v3.0.
The nearest watercourse on the river map is the River Ray, about 10 m from the middle of Grendon Underwood's gauges. It flows into the River Cherwell about 23 km downstream.
A gauge downstream shows water that has already passed this point; one upstream sees it first. Distances along the river are from the point on the River Ray nearest the middle of Grendon Underwood's gauges. From Ordnance Survey’s river map (OS Open Rivers), which leaves out small streams, ditches and culverts, so a nearer one may exist. This describes where water goes on the map; it says nothing about flooding at any address. Contains OS data © Crown copyright and database rights 2026.
Grendon Underwood is monitored by 1 Environment Agency river level station on the River Ray, in Buckinghamshire. Water levels are updated every 15 minutes, providing real-time flood monitoring for the area.
The River Ray is monitored by 1 station (Grendon Underwood). Each station records water levels continuously, with data synced to FloodRadar every 5 minutes.
There are 3 Environment Agency flood warning areas within 10km of Grendon Underwood. When the EA issues a flood warning for any of these areas, it will appear on this page. These include: River Great Ouse from Brackley to Thornborough, including Padbury Brook; River Ray and its tributaries from Shipton Lee to Islip, including Ludgershall, Blackthorn and Murcott; River Ray from the Heath Bridge area to and including the Otmoor Basin.
There are 3 storm overflows within 5km of Grendon Underwood. None of the 3 with a reporting monitor are currently discharging. Enable "Sewage" on the map above to see their locations.
Each has its own page of live status and past discharges:
If flooding is forecast in Grendon Underwood, call Floodline on 0345 988 1188 for the latest information. Move valuables upstairs, turn off gas and electricity if safe to do so, and avoid walking or driving through flood water. Sign up for flood warnings on any station page above to receive email alerts when water levels rise. For emergency numbers, a preparation checklist and insurance guidance, see our flood help & preparation guide.
Grendon Underwood gets about 647 mm of rain a year on average (wettest month October, 67 mm; driest March, 40 mm). That is 44% drier than the UK as a whole, which averages 1,163 mm a year. See the rain gauges →
A thirty-year average for the area, not a forecast and not a flood risk on its own. Source: Met Office HadUK-Grid 1991–2020 (5 km grid), 1.4 km away. Average rainfall: HadUK-Grid v1.3.2, Met Office. Contains public sector information licensed under the Open Government Licence v3.0.
Floods whose mapped extent (EA Recorded Flood Outlines) reached within ~5 km of the town centre — most recent first. These are records of mapped extents, not a full list of floods. See them on the map →
Records, not floods: no outline on the record is not evidence a place has not flooded.
Current verdict: Normal. No official flood warning is active nearby and the closest river stations are within normal ranges.
Grendon Underwood has river level monitoring on River Ray — 1 monitoring station in total.
Use the GOV.UK Check for Flooding service (check-for-flooding.service.gov.uk) or call Floodline on 0345 988 1188 (24 hours). You can also set up free FloodRadar email or browser alerts from any station page above.
Follow official advice: move valuables and vehicles to safety, never walk or drive through flood water, turn off gas and electricity if safe, and check on vulnerable neighbours. See our flood preparation guide at floodradar.co.uk/flood-help.
No recorded flood outline is mapped around the Grendon Underwood town centre means no flood was mapped here, which is not evidence none happened: the Environment Agency mapped only some floods, mapping effort rose sharply after about 2000, and surface-water flooding is largely absent from this record. FloodRadar has separately logged 10 flood warnings or alerts for the Buckinghamshire area since February 2026. See the flood history link below.
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